1. Field of the Invention
The present invention relates to a timepiece equipped with a calendar mechanism including a first date indicator for displaying the ones digit of the date and a second date indicator for displaying the tens digit of the date.
2. Description of the Prior Art
Generally, the mechanical body of a timepiece including the drive portion of the timepiece is referred to as the “movement”. A dial and hands are attached to the movement and put into a timepiece case, forming a complete product. This state is referred to as the “completed” state of the timepiece. A main plate forms the base plate of the timepiece. The side of the main plate which faces the timepiece case glass or on the side of the dial is referred to as the “back side”, “glass side”, or “dial side” of the movement. The other side of the main plate which faces a case back of the timepiece (i.e., which faces away from the dial) is referred to as the “front side” or “case back side” of the movement. A train wheel incorporated into the “front side” of the movement is referred to as the “front train wheel”. A train wheel incorporated into the “back side” of the movement is referred to as the “back train wheel”.
Hereunder, it is explained about a constitution of the timepiece with the calendar mechanism containing the 1st date indicator displaying the place of units among dates, and the 2nd date indicator displaying the place of tens among dates.
(1) Timepiece with Conventional 1st Type Calendar Mechanism
A timepiece with a conventional 1st type calendar mechanism possesses a dial having a large window, and a rotating body (i.e., 1st date indicator) for the place of units in which there are disposed 31 numerals containing one numeral of “1” and 3 sets of numerals of “1” to “9” and “0” and there are provided 4 teeth, and additionally possesses a star-shaped plate for the place of tens having 4 teeth, and a rotating body (i.e., 2nd date indicator) for the place of tens in which there are disposed numerals of “0”, “1”, “2”, “3”. The rotating body (i.e., 1st date indicator) for the place of units is directly rotating the rotating body (i.e., 2nd date indicator) for the place of tens (for example, refer to Japanese Patent No. 3390021 Gazette).
(2) Timepiece with Conventional 2nd Type Calendar Mechanism
A timepiece with a conventional 2nd type calendar mechanism contains a 1st date plate (i.e., 1st date indicator) displaying the place of units of dates, a 2nd date plate (i.e., 2nd date indicator) displaying the place of tens of dates, a date unlocking wheel driving the 1st date plate, an unlocking pawl provided in the 1st date plate, an intermediate wheel driven by the unlocking pawl, a 1st jumping control lever rotating the 1st date plate from an unlocking midway and causing it to remain in a stabilized position, and a 2nd jumping control lever rotating the 2nd date plate from the unlocking midway and causing it to remain in a stabilized position. In the 1st date plate (i.e., 1st date indicator), there are disposed 20 numerals containing two sets of numerals of “1” to “9” and “0” (for example, refer to JP-A-2000-314779 Gazette).
(3) List of Patent Documents
Hereunder, there is shown a list of the Patent Documents relating to the timepiece with the conventional calendar mechanism mentioned above.
(1) Problems of Timepiece with Conventional 1st Type Calendar Mechanism
Since the timepiece with the conventional 1st type calendar mechanism possesses the rotating body for the place of units in which there are disposed 31 numerals containing numeral of “1” and 3 sets of numerals of “1” to “9” and “0”, a time at which the calendar mechanism must be corrected at the end of the month is respectively the end of February, April, June, September and November. That is, the number of times at which the calendar mechanism must be corrected is 5 times per year. However, in the timepiece with the conventional 1st type calendar mechanism, since the rotating body for the place of units directly rotates the rotating body for the place of tens, it has been impossible to dispose such that the rotating body for the place of units and the rotating body for the place of tens have the same rotation center. Accordingly, in this structure, when designing the two rotating bodies, there has been generated a restriction in a position where the date can be displayed by the 2 rotating bodies.
(2) Problems of Timepiece with Conventional 2nd Type Calendar Mechanism
In the timepiece with the conventional 2nd type calendar mechanism, in the 1st date plate, there are disposed two sets of numerals of “0” and “1”–“9”, i.e., 20 numerals. Accordingly, the time at which the calendar mechanism must be corrected at the end of the month is respectively the end of every month. That is, the number of times at which the calendar mechanism must be corrected is 12 times per year.